I’m intrigued how it would have made a difference, wouldn’t it be extremely trivial to “clean up” the dataset by just doing a regex and removing all the “+*”. Or are scammers that lazy? Maybe I’m missing something?
Look at all the comments from the web devs saying they don't go out of their way to disallow this. Their situation is about the same as here.
It's just an edge case you'd have to devote brainpower and resources to. It may not be a big commitment, but if it only nets you an additional 0.25% valid email addresses or something, it's probably not going to get done.